Form crushing of abrasive wheels



p 1945. G; F. EGLINTON 2,384,289

FORM CRUSHING OF ABRASIVE WHEELS F'iled Nov. 5, 1943 2 Sheets-Sheet l INVENTOR 22 61 0 6 F2 7, BY

A TTORNE K5.

Sept. 4, 1945. I

e. F. EGLINTON 2,384,289

FORM CRUSHING OF ABRASIVE WHEELS Filed Nov. 3, 1943 2 Sheets-Sheet 2 6 1 INVENTOR- 420, 8 2' ilm BY E k I J3 M ATTORNEYfi Patented Sept. 4,

FORM CRUSHING OF ABRASIVE WHEELS George F. Eglinton, Detroit, Mich assignor, by mcsne assignments, to Lincoln Park Industries,

inc, Lincoln Park, Micln,

Michigan a corporation of Application November 3, 1943, Serial No. 508,785

7 @laims.

usually maintained within close precision limits is required. in grinding arcuate forms having small radii extreme accuracy in forming the form gencrating surfaces of the grinding wheel is of particuiar importance.

The principal object of the present invention is to provide an improved method and apparatus for crushing a form generating surface in the workins; surface of an abrasive grinding wheel which method is relatively simple to carryout by the use oi apparatus herein disclosed which assures the generation at true forms within close precision limits by the use of readily available'extraded forms which are continually renewed durting the form crushing operation so that-a predetermined contour is formed in the grinding surface witlun close precision limits.

Qther objects oi this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate correspondingpartsin the several views.

In the drawings:

Fig. 1 is a fragmentary view partially in side elevation and partially in section showing one form of apparatus embodying the present inventlon.

Fig. 2 is a plan view partially in section taken substantially along the staggered line 2-2 looking in the direction of the arrows in Fig. 1.

Fig. 3 is a front elevation of the apparatus shown in Fig. 1.

v Fig. 4 is a section taken substantially on the lll ine g-4 looking in the direction of the arrows of Before explaining in detail the present invention it is to be understood that the invention is not limited inits application to the details of construction and arrangement of parts illustrated tion is capable of other embodiments and of being practiced or carried out invarious ways. Also it is to be understood that the pbraseology or terminology employed herein is forthe purpose of da scription and not of limitation.

The apparatus shown in the accompanying and 2| by the manually actuated reel 25 which is in the accompanying drawings, since the invcndrawings also is a schematic representation of the novel method of form crushing a grindin ur- I face of a grinding wheel which embodies the present invention. The method consists essentially in drawing an elongated form generating wire of desired shape and dimensions over the grinding surface of an abrasive wheel which is-held against the form generating wire at a predetermined pressure which may be varied according to the composition of the abrasive wheel but which is sumcient to cause the wire to embed itself progressively into the grinding surface of the wheel without fracturing the said wheel. The abrasive wheel is free to rotate as the wire is drawn over the grinding surface so that the peripheral speed of the wheel is the same as the lineal speed of the wire.

Such a method is carried out satisfactorily by the use of the apparatus shown in the accompanying drawings. This apparatus comprises a fixed table it on which is mounted a base ii having. a vertically extending flange IE on which is secured the yoke of a spooling frame it which is mounted for pivotal adjustment relative to the flange i2 and the base it. The spooling frame it includes a-vertical bracket IS on the end of which is mounted a spool it of extruded wire ll of a desired contour and dimension to provide the desired shape in the working surface of the grinding wheel. A second bracket it of the spooling frame it carries the rotatably mounted idler rollers I9, 20 and 2|, which guide the wire I! over a pressure roller 22 which holds the wire l'l in position for contacting the working surface 23 of an abrasive wheel 24 which is held against said wire I! at a desired adjusted pressure which is sufllcient to cause the wire ii to become progressivelyembedded therein to the desired extent during the crushing operation, while permitting the wheel 24 to revolve as the wire I I isdrawn over it. a

.The roller 22 is provided with wheel supporting flanges 22a and 22b which support the side edge portion of the wheel 24 during the form crushing operation.

The wire i1 is drawn over the working surface of the grinding wheel24 and the rollers I9, 22, 20

driven by a hand crank 28 and mounted on a third bracket 21 of the spooling frame l4.

Tension on the wire I1 is controlled by a manually adjustable brake on the spool l6, which as shown in Figs. 3 and 4 comprises a friction disc 34 mounted on the face ofa plate 3i carried on a push rod 32, which is moved toward or away the pressure roller 22.

from the spool l6 by actuation of the knurled knob 33 keyed to said rod 32. An extending end 34 of the rod 32 extends into the central hole in the hub of the spool I6, and supports one side .of said spool for rotation in said bracket I 5. The

opposite side of said spool is supported for rotation in said bracket by an extending end 35 carried on an axially movable plunger 36 which is movable toward and away from an adjacent face of the-spool by actuation of an adjusting collar 31 having a plurality of arcuate slots 38 extending through the periphery thereof and each engaging with one of a plurality of radially extending studs 39 carried on the axially movable plunger 36.

Movement of the adjusting collar 31 thus moves the plunger 36 as may be required to bring the extending end 35 into registration with a central hole in the hub of the spool I6 and thus permits the use of the device with spools of different widths.

The apparatus as here shown is adjusted to crush a straight line circumferential groove in the working surface of the abrasive wheel 24. Such a gl'OOVe in the wheel 24 will generate a rounded flange or rib on the surface of a work' piece which is ground by the wheel 24. In certain uses it is desired to grind a spiral thread with such a surface. To accomplish the grinding of aspiral thread on the work piece, the form generated grinding surface on the grinding wheel extends angularly across the grinding surface of the grinding wheel at such an angle as to generate an inclined spiral thread surface on the work piece. To crush such a form into the grinding surface, the spooling frame I4 is moved pivotally into an adjusted angular position relative to the base ll so as to hold the wire I! at an angle to the working surface 23 of the abrasive wheel 24. This angle is determined in such a manner that the groove which is crushed in the working surface 23 of the abrasive wheel 24 will extend both angularly across the working surface as well as circumferentially around the working surface. This is accomplished :by loosening the adjusting screw 60 and moving the frame M to the desired position as indicated on the calibrated dial plate 4| secured to the base H. A guide plate 42 is secured to the movable spooling frame [4 and has an arcuate guide slot 43 through which extends the guide pin 44 for guiding the pivotal movement of the frame l4 and also for providing a stop to prevent the movement of said member beyond a predetermined limit.

The operation of the apparatus herein described is as follows: The extruded wire I1 is selected to provide the desired contour to be formed in the grindin surface 23. This form may be circular in cross-section as here shown or it may be triangular, rectangular, hexagonal, or of the like or similar forms in cross-section. The extruded wire I] isthreaded overthe rollers I9, 22,

20 and 2| to the reel 25. The spool (brake is adjusted to hold the spool l6 against free rotation and the manual crank 25 is turned to rotate the reel 25 and build up the desired amount of tension in the wire ll. The grinding surface 23 of the abrasive wheel 24 is adjustably pressed against the portion of the wire I! which overlies This. pressure is sufficient to cause the wire I1 to become embedded therein during the form crushing .operation, but it is not sufficient to cause the wheel 24 to become fractured. The wheel 24 is free to rotate as the .wire

I! is drawn over its surface 23. Rotation of the reel 25 by actuation of the hand crank 26 draws the wire I I over the contacting surface 23 of the abrasive wheel 24, which, because of its frictional contact with said wire, is caused to rotate at the same peripheral speed as the lineal speed of movement of said wire. The operator can determine by the amount of force required to operate the hand crank 26, the extent of frictional engagement between the wire l1 and the working surface 23 of the abrasive wheel '24. This permits the operator by suitable adjustment to vary as may be required, the pressures which are exerted 'by the abrasive wheel 24 on the wire [1. The operation progresses by drawing the wire I! continually over the working surface 23 until the desired form is generated therein. During this form generating operation, it will be observed that a new wire surface is presented continually to the working surface 23 of the wheel 24 so that at all times a true wire form is available for generating the form in the working surface 23. The

selection of various sizes and shapes of extruded V wire I! thus permits the use of the present anparatus and the present method in the formation' of various desired types of forms in the working surface 23 of the abrasive wheel 24.

The method and apparatus proposed herein thus provides a relatively simple and economical means for generating a desired form in the working surface .of a form grinding abrasive wheel and assures the generation of such form therein within close precision limits. The use of a continually renewed crushing form to impart the desired form to the working surface of the abrasive wheel also assures the uniform development of such form in said wheel.

Having thus described my invention, I claim:

1. In the method of crush forming the work- 0 ing surface of a bonded abrasive form grinding wheel, the novel step of continually drawing a selected extruded wire form over the working surface of said wheel to effect the rotation thereof while exerting a controlled pressurethereon sufllcient to embed said wire in said wheel but insuflicient to cause its fracture.

2. In the method of generating a form in th working surface of a form grinding wheel, the novel step of continually drawing a selected extruded wire form over the working surface of said wheel while exerting a controlled pressure thereon sufiicient to embed said wire in said wheel but insuflicient to cause its fracture, while permitting rotation of said abrasive wheel at a peripheral speed substantially equal to the lineal speed of drawing said wire over said working surface.

3. An apparatus for generating a form in the working surface of a form grinding wheel and comprising a base, a spooling frame secured thereto and including a spool holding bracket, a roller bracket and a reel bracket, a wire holding spool mounted for rotation in said spool holding bracket, a plurality of guide rollers and a pressure roller mounted for rotation in.said roller bracket and a reel rotatably mounted in said reel bracket, and a form generating wire threaded from said spool over said guide rollers and said pressure roller and into said reel. whereby upon rotation of said reel, the wire is drawn from said spool and over said premure roller.

4. An apparatus as claimed in claim 3 and further characterized in that a wire tensioning brake is mounted adjacent said spool to exert a braking efiect on the rotation thereof.

5. An apparatus as claimed in claim 3 and further characterized in that the spoofing frame is mounted for adjustable pivoting relative to said base to vary the direction of the path of said wire angularly relative to said base.

6. An apparatus as claimed in claim 3 and further characterized in that a wire tensioning brake is mounted adjacent said spool to exert a braking efiect on the rotation thereof and means are provided to control said brake to vary 10 tion thereof. v

GEORGE F. EGLINTON. 

